Electromagnetic relay



Nov. 11, 1941.` c vH. LAR'sON 'ELECTROMAGNETIC RELAY Filed `March 29, 1937 NN NN QM .WN WN @N @N @IN tgl .SQ N

Patented Nov. 11, 1941 ELECTROMAGNETIC RELAY Carl H. Larson, Elkhart, Ind., assignor to The Adlake Company, a corporation of Illinois Application March 29, 1937, Serial No. 133,593

9 Claims.

Primarily, this invention relates to two-light blinkers such as used on automobile highways to flash a warning for sharp curves, permanent obstructions, or the like, but the invention is also capable of other uses.

Blinkers are ordinarily operated from, a local source of electromotive force such als a battery, and in order to minimize the cost of maintenance, it is necessary for the blinker relay to operate on relatively little power. In the present invention, this result is achieved by employing novel circuit breakers in a circuit which provides relatively short periods of energization for the relay, and substantial dark periods between theflashing of alternate lights.

Further and other objects and advantages will become apparent as the disclosure proceeds and the description is read in conjunction with the accompanying drawing, in which:

Fig. l is a diagrammatic view showing a preferred form of the invention;

Fig. 2 is an abridged View showing the position of the switch parts at the instant when the magnetic circuit collapses and the displacers are about to fall by gravity to their lower positions;

Fig. 3 illustrates the manner in which the displacer of the second circuit breaker overshoots its mark to momentarily close the contacts through the switch; and

Fig. 4 is a diagram illustrating the relative periods of lamp illumination.

The disclosure in the accompanying drawing, taken in conjunction with the description which follows, is in compliance with the provisions ot sec. 4888 of the Revised Statutes, but the claims should be construed as broadly as the prior art will permit.

In the illustrative embodiment of the invention, lamps I and II are adapted to be alternately flashed by a relay generally designated I2, operated from. a source I3 of electromotive force, as for example, a battery.

The relay comprises a magnetic or iron circuit I4 adapted to be energized by a coil I5 which, in the present instance, is wound on separate legs of the magnetic circuit. The winding of the coil is such that when energized, a strong magnetic flux is set up between the top and bottom pole pieces I6 and I'I, respectively, of the iron circuit, and it is this ilux which is adapted to operate the two switches I8 and I9 of the relay.

'Ihe switch I8 is a self-acting intermittent circuit breaker, i. e. in normal use, it maintains a certain frequency of operation. The second circuit breaker IB may be termed an inertia switch for it relies upon the inertia of one of its moving parts to close the circuit which it controls.

Although the switches I8 and I9 are shown as mercury switches in the illustrative embodiment of the invention, and as such, contribute to the economical and satisfactory operation of Ithe blinker, other types of switches may b'e used, as will readily be understood from the teachings of this invention.

The switch i8 comprises a switch envelope 20, preferably of boro-silicate glass, through the base of which electrodes 2| and 22 are suitably sealed, the latter being surrounded for a portion of its length by an insulating sleeve 23 which leaves the upper end 24 of the electrode bare. The envelope contains a quantity of mercury 25 and a gas ll, such as helium, hydrogen, or a combinationof the two, and after all parts of the switch hav'e been assembled, the envelope is` sealed off as indicated at 26.

A magnetically responsive displacer or armature 21 of high quality Swedish iron having a time delay element 28 of the type disclosed in Larson Patent No. 1,967,947, is adapted vto reciprocate within the switch envelope in response to the coil I5, the displacer being telescoped over the electrode 22, as best shown in Figs. 1 and 3. Springs 29 and 30 are provided in the switch envelope to protect the ends of the envelope from damage by the displacer during shipment, the former being mounted on the displacer and the latter being mounted on the central electrode 22 in Xed relation to the switch envelope.

The electrode 2| of the switch I8 is permanently connected by a conductor 3| to one side of the battery I3, and the electrode 22 is connected by a conductor 32 .to the other side of the battery through the lamp I0. The coil I5 is in parallel with the lamp I0 so that whenever the mercury bridges the electrodes of the switch I8, not only is the lamp I0 illuminated, but also the coil I5 is energized to lift the displacer 2T to the position shown in Fig. 2. In making this upward stroke, the displacer momentarily carries with it the mercury which has found its way into the bottom of the displacer by the slow leakage of gas through the ceramic thimble 28, but as soon as the displacer has been lifted sufliciently by the magnetic flux to permit gas to enter the displacer through the bottom opening 33, the mercury in the displacer is rshowered upon the bared end 24 of the electrode 22 and maintains the electrical circuit through the switch for a period of time which corresponds to that required for lifting the displacer and permitting the mercury to fall when the gas enters the interior of the displacer through the opening 33.

As soon as the circuit through the electrodes 2| and 22 is opened by the falling away of mercury from the raised armature or displacer (the mercury level being normally below the top of the insulating sleeve 23) the lamp I8 is extinguished and the coil I5 de-energized, whereupon the displacer falls to the position shown in Fig. 3, forcing the mercury away from the bared end 24 of the electrode 22 and creating a difference between the level of the mercury on the outside of the displacer and that on the inside of the displacer which tends to become equalized by the slow passage of the gas entrapped within the displacer through the ceramic thimble 28. As soon as the mercury on the inside of the displacer reaches the bared end 24 of the electrode, the displacer is lifted and the cycle is repeated. makes the switch I8 a self-acting intermittent circuit breaker.

Although the switch E8 is ordinarily termed a slow make, quick break circuit breaker, the fact is that there is a short time delay in the breaking of the circuit due to the lifting of a quantity of mercury within the displacer on its upward stroke and the subsequent falling away of mercury when gas enters the bottom of the displacer.

Instead of using a time delay element attached to the armature of the switch, it is possible to use a time delay element which is fixed with respect to the switch envelope, as for example, the type shown in Fig. 7 ci Larson Patent No. 1,967,946.

The description thus far shows the manner in which the lamp I0 is iiashed by the switch I8 and obviously the disclosure is suilicient to indicate how a one light blinker may be operated.

The inertia switch I9 comprises a switch envelope 34 through the base of which electrodes 35 and 35 are sealed, the latter being surrounded by an insulating sleeve 3l for a portion of its height and terminating in a cup 38 adapted to contain a quantity of mercury 39 which is constantly in contact with the electrode 36.

The envelope contains a mercury ll 40, the level of which is adapted t0 be changed by an armature or displacer 4I consisting of a tube of magnetic material telescoped over the central electrode 36. The switch I9 has springs 29 and for the same purpose as described with ref erence to the switch I8.

The moving parts of the switch I8 may be said to have two positions oi equilibrium, one in which the coil I5 is de-energized, and the displacer is in the position shown in Fig. l; and the other in which the coil I5 is energized and the displacer is in the position shown in Fig. 2. In both of these positions, the mercury level is such that the mercury 39 in the cup 38 is not in contact with the main body of the mercury ll 40, so that the circuit through the electrodes and 36 is open. However, when the displacer 4I falls from the position shown in Fig. 2 by deenergization of the coil I5 in response to the action of the switch I8, the inertia of the displacer carries it to the position shown in Fig. 3 causing the main mercury iill to come in contact with the mercury in the cup 38 and thereby close the circuit through the electrodes 35 and 36 for a period of time which corresponds to the time required for the displacer to return to its lower position of equilibrium, as shown in Fig. 1.

It is this characteristic action which The mercury to mercury contact at the central electrode 36 retards the opening of the circuit through the electrodes 35 and 36 by reason of the surface tension of the mercury.

The electrodes 35 and 36 of the inertia switch I9 are connected across the battery I3 in series with the lamp I I so that the lamp is illuminated for the period of time corresponding to the closing of the circuit through the electrodes 35 and 36.

It will thus be seen that the lamp III is illuminated by the switch I8 as the armatures 21 and 4I are moving upwardly in response to the coil I 5 and that the lamp II is illuminated when the armature 4I of the switch I9 overshoots its mark by reason of its inertia.

The principle used in the inertia switch I9 may be embodied in various forms, as for example, electromechanical relays and tilting type mercury switches. All that is required is that the inertia of a moving part of the switch or relay be utilized to establish the contact of predetermined duration, and that the two positions of equilibrium for the switch parts result in an open circuit condition through the switch or relay.

The economy of operation of a blinker made in accordance with this invention is illustrated in the diagram of Fig. 4. Plotting the inertia switch above the datum line, and the control switch below, both with reference to time, it will be seen that under illustrative conditions requiring sixty flashes per minute, the lamp I0 may lash for three-tenths of a second, followed by a dark period of seven-tenths of a second; and during the dark period of the lamp I0, the lamp II will flash for three-tenths of a second, followed by a dark period of seven-tenths of a second, etc. The period during which the relay is energized is represented by the period during which the lamp I Il is illuminated, viz. threetenths of each second, or substantially less than one-half of the entire time that the blinker is operated. Obviously, under such conditions, the blinker has a low operating and maintenance cost.

The diagram of Fig. 4 shows that not only are all light ilashes of equal duration, but that the dark zones are also of equal duration. This result is achieved by correctly proportioning the switch parts, using the proper mercury ll, time delay element, armatures, etc., some of which data, listed below (although illustrative only), will aid persons skilled in the art to readily practice the invention.

Switch 18 (self-acting intermittent circuit Mercury level, when displacer is raised, approximately below edge of cup 38. Mercury level, when displacer is in lower position of equilibrium, approximately below edge of cup 38.

From the specific data given above, other parts of the relay may readily be ascertained, but it will be understood that the speciiic data given is in compliance with sec. 4888 of the Revised Statutes, and does not impose limitations upon the appended claims.

It should be noted that in the embodiment of the invention shown, the inertia switch I9 closes and opens the circuit which it controls before the coil l is re-energized to lift the armature 4l.

I claim:

1. In combination, a source of electromotive force, a pair oi lamps, and relay means for alternately flashing said lamps, said means including a self-acting intermittent circuit breaker controlling one of the lamps, a magnetic flux inducing circuit controlled by said circuit breaker, a second circuit breaker controlled by the magnetic iluX, said last named circuit breaker closing to energize the other of the lamps for a fraction of the period of time the flux inducing circuit is open.

2. In a blinker, a source of electromotive force, a pair of lamps, a relay including an operating coil for alternately flashing the lamps, said relay comprising a self-acting intermittent circuit breaker having a retarded closing controlling the coil and one of the lamps, a second circuit breaker having a quick making back contact which controls the other lamp, and means associated with each of the circuit breakers for momentarily retarding the opening of the circuit through the respective circuit breakers.

3. In combination, a source of electromotive force, a pair of lamps, and relay means for alternately liashing said lamps, said means including a self-acting intermittent circuit breaker controlling one lamp, a magnetic flux inducing element controlled by said circuit breaker, a second circuit breaker controlled by said magnetic flux, said last named circuitbreaker controlling the other lamp and being adapted to close and reopen after the condition of the magnetic iiux has been changed and before the original condition of the magnetic flux is restored.

4. In combination, a source of electromotive force, a pair of lamps, a relay means for alternately flashing said lamps, said means including a magnetic flux inducing circuit and a self-acting intermittent circuit breaker opening and closing the magnetic flux inducing circuit and the circuit through one of the lamps, a second circuit breaker controlled by the magnetic ux and controlling the other lamp, the second circuit breaker being adapted to close the circuit through the lamp Which it controls for a predetermined period of time only whenever the lux collapses, said period of time being less than the duration of the open period of the self-acting intermittent circuit breaker.

5. In a flasher, a source of electromotive force, a pair of lamps, and relay means for alternately flashing said lamps, said means including a magnetic iiux inducing circuit, a self -acting intermittent breaker controlling the magnetic circuit and one of the lamps, a second circuit breaker associated With the magnetic circuit and adapted to control the other lamp, said last named circuit breaker including contacts, an element for bridging the contacts and an armature controlling said element, said armature and element opening the contacts after the circuit has been deenergized for a given period of time, and said armature moving said element into a position temporarily closing the contacts by inertia after said de-energization of said circuit.

6. In combination, a source of elmtromotive force, a pair of lamps, and relay means for alternately flashing said lamps, said means including an electromagnet intermittently energized along with one of the lamps, a circuit breaker for the other lamp operated by the magnet including contacts and an element controlled by said electromagnet for movement through a predetermined cycle by the energization and de--energization of the electromagnet, means operated by said element for closing the contact for a iractional portion of the period of time the operating coil for the circuit breaker is de-energized.

'7. In a ilasher, a source of electromotive force, a plurality of lamps, a relay means for flashing said lamps successively and in a predetermined order, said means including a magnetic flux inducing circuit, a self-acting intermittent circuit breaker controlling the flux inducing circuit and one of the lamps, a second circuit breaker associated with the flux inducing circuit and adapted to control another lamp, said last named circuit breaker including contacts, an armature responsive to said iiuX, and an element controlled by said armature for bridging said contacts, said armature performing a cycle each time the magnetic circuit is energized and de-energized, including a position wherein the contacts are open after the flux characteristics of said circuit have remained constant for a given period of time, said armature moving said element to bridge the contacts in said cycle immediately prior to the time said position is attained.

8. A relay comprising a coil, a switch envelope, a mercury lill in the envelope, spaced contacts capable of being closed by contact with the mercury lill, an armature having two positions of equilibrium depending upon the state of energization of the coil, one of said contacts being above the level of the mercury lill at both positions of equilibrium and said armature moving the mercury into a position simultaneously engaging the contacts when moving from one of said positions of equilibrium to the other.

9. A relay comprising a coil, an envelope, a mercury lill in the envelope, spaced contacts in the envelope capable of being bridged through engagement with the mercury iill, an armature within the envelope and responsive to the field of the coil having an upper and lower position of equilibrium at neither one of which the mercury is in engagement with the contacts simultaneously, said armature moving the mercury into a position simultaneously engaging the contacts when the armature is moved from one of said positions of equilibrium to the other.

CARL H. LARSON. 

